1. Field of the Invention
The present invention relates to a pumping system whose output is regulated by gas provided by a gas source.
2. Description of the Related Art
In semiconductor processes, liquid supply is very important. For example, in chemical mechanical polish (CMP) and etching processes, it is very important to provide slurries and etching solutions accurately. Typically, conventional pumps are controlled by signals. Conventional pumps, however, cannot always output liquid stably because of unstable pressure caused by pulse signals. Thus, devices, for example, may be overetched or not etched completely if the liquid supply is not controlled accurately.
In view of this, an object of the present invention is to provide a pumping system with stable output. The present invention uses a plurality of switching devices to stably control the operation of a cylinder pump and its output.
Further, the present invention can control the speed of the cylinder pump by adjusting the gas flow of the needle valve. In addition, the present invention can control the output of the cylinder pump by adjusting the position of the hard stop at the piston linkage.
In the present invention, the pumping system pumps liquid and outputs regulated by gas provided by a gas source. The pumping system has a cylinder pump, a first group of switching devices, and a second group of switching devices. The first group of switching devices enable the cylinder pump to pump the liquid by feeding the gas provided by the gas source into the cylinder pump through a first ventilator according to a first enabling signal, and the second group of switching devices enable the cylinder to output the liquid by feeding the gas provided by the gas source into the cylinder pump through a second ventilator according to a second enabling signal. A control unit is coupled to the first and second groups of switching devices, and controls the gas entering and leaving the cylinder pump and the flow speed of the gas.